Im wondering whats the difference between dynos. People tell me you cant say your # is weaker or stronger from dyno to dyno but from what I understand there is a difference. Don M on a thread earlier I think said someone dynoed higher 75Hp or something on the dyno I hit mine #s on compared to what ever dyno they were hitting. I also know that the guy who runs the dyno in my area is great and very competent at what he does. Great guy. We just had a diesel event up here sponsored by Poncis diesel recently. a chevy who had 705HP only hit 630 or so on the Super FLow. So if any one can educate I would like to figure this out. People are always telling me the dyno I go to is hard and everyone leaves thinking no way is my # that low. Im looking for a census from the DTR guys about dynos. Thanks.

 

Do a search on here about dyno's. There's one thread that has some good info about the differences.

 

I am no dyno expert. I can just tell you my experiences.

I have been on several dynojets....and I trust their numbers. One dynojet I was within 3 hp of what I dyno'd a year earlier on....stock vs. stock.


I dyno'd on a Mustang and my numbers were way to high. It made me feel good at the time, but when I learned the truth........I realized I had just wasted my money.


Like Don M mentioned in that thread.......you can run on a dynojet anywhere in the country and have something to compare your true numbers too.

 

Yeah but what Don M did not mention is that when you have those #'s on a super flow win there even that much better to compare to the rest of country as you say. My superflow win dyno #'s will be higher on any dyno I hit dynojet or mustang. Super flow win is the hardest dyno to put high #'s on. Its the most accurate dyno out there. I know for a fact other people who dynoed on a dynojet hit 70 less Hp on the superflow. I heard its never that much but someone came to our hometown superflow dyno and hit around 630 when they also hit 704 or so on a dynojet.

 

I like the inertia dyno's myself. I dont have to worry about blowing anything up on them and its easier on the drive train.

 

Dynojet all the way. If they dyno 70 Hp less on a load dyno, I would be shocked. Most load style dyno's dyno a little higher actually from putting a better load on the engine allowing it to work.

 

Another advantage of the dynojet is that is a darn consistent. I have not seen that with load dynos.

 

Something else that can cause variations are correction factors - mathematical corrections for elevation (barometric pressure) and ambient temperature, both of which affect air density. These correction factors were established for naturally aspirated engines but can overstate dyno results for our turbo diesels which don't lose power with changes in elevation at the same rate as a naturally aspirated engine. That's why the measly dyno results in my signature for my pore ole trailer dragger are quoted as uncorrected. Another member had the same package and generated 390/900 "corrected" results at a dyno in the Rocky Mountains.

Rusty

 

If you can read past Gale Banks' bias against inertial chassis dynos, here's a writeup that sorta lays out the differences between a load and inertial chassis dynamometer: Banks on Dynos.

Rusty

 

Thanks for the right up. Yeah Im sure you have heard of Nick D amico. He has 705RWHP and he went to the Northern California dyno event on the Super Flow win chasis dyno and he only hit around 630. Now Im not saying the dyno is off 70HP but I do know the only # my dyno guy gives you is corrected. So with that said that guy came up to our dyno with what Im guessing was a 705 uncorrected on a dynojet. So with the correction and change from dynojet to superflow win he lost 70Hp or so.

 

For tuning a Superflow is top notch.

For comparison sake you can only use a dynojet. The dynojets are very similar from state to state and dyno to dyno.

There are too many factors that can change on load dynos to try and compare from state to state or dyno to dyno.

They all have different math and drum weights and there are many factors that the dyno operators do not input like the frontal area of a vehicle.

 

I went to a dyno meet once (Mustang dyno) and the numbers were obviously screwed up! Only the auto trucks put out good numbers and all the stick trucks were WAY low. I don't understand dynos but I know what brake hp is. I got them to do a "constant speed" run with my truck and the numbers came way up. That seemed more like true brake hp cuz it wouldn't let the truck go above the preset speed. Someone, please explain what corrected and uncorrected hp means. Craig

 

Uncorrected horsepower is what you are actually putting to the rollers. Corrected horsepower uses mathematical correction to bring the results back to "standard day" conditions. Depending on whose standard day you're talking about, that could be 59 degF and sea level, or 80 degF and 1500 ft elevation, or something else. So, corrected horsepower equals uncorrected horsepower X temperature correction factor X barometric pressure correction factor.

Rusty

 

wow there chief no one did any math equations my power is what was on the computer screen. Im pretty sure that my dyno guy told me that my numbers are corrected whats at the rollers. He told me uncorrected HP usually is a higher # than what the rollers are doing. Are dyno is a Super Flow Win at sea level with a 25% load I think. Dyno guy told me there is no need to make any corrections. So maybe I mixed up what corrected v.s uncorrected is.

 

That can't be true because it totally depends on where the dyno is. The same thing cannot be said for a dyno @10,000ft. and 1% humidity when it's 35° out as compared to a dyno at -100ft. and 100% humidity when it's 95° out. It all depends.